'What on earth': Novak Djokovic survives 'terrible' drama at US Open

Tennis fans were left gobsmacked while watching the US Open on Monday when Novak Djokovic produced an error-strewn display to drop the first set against Jenson Brooksby in their fourth-round clash.

Not many were giving American young gun Brooksby much of a chance against the World No.1, but the 20-year-old stunned Djokovic to take the first set 6-1 in just 30 minutes.

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Djokovic was broken three times in barely-believable scenes as Brooksby sent the Arthur Ashe Stadium crowd into a frenzy.

"That was a terrible game," one commentator said on ESPN as Djokovic dropped his serve to go down 5-1.

"This is getting worse by the second for Djokovic."

John McEnroe added: "You'd be hard-pressed to find anyone who would believe Brooksby would be the one playing like this."

Fans flocked to social media in utter disbelief as Brooksby stormed to a one-set lead.

Thankfully for Djokovic fans the 20-time grand slam champion managed to right the ship, advancing to the quarter-finals with a 1-6, 6-3, 6-2, 6-2 victory.

The Serbian star looked a completely different player from the second set onwards, while Brooksby appeared to struggle with the physicality of the gruelling match.

Djokovic is now just three matches away from completing the first men's singles calendar-year Grand Slam in 52 years.

The 34-year-old would become the first man since Rod Laver in 1969 to sweep all four major titles in the same year by capturing his fourth career US Open crown.

He is also going for a men's singles record 21st Slam trophy, which would boost him one ahead of "Big Three" rivals Roger Federer and Rafael Nadal, both absent with injuries.

Djokovic is now on a 21-match win streak against American players.

Zverev and Berrettini move into US Open quarter-finals

Earlier, Alexander Zverev moved into the quarter-finals by beating Jannik Sinner 6-4 6-4 7-6 (9-7), getting a step closer to a maiden slam title.

Zverev started a 15-match winning streak at the Olympics, carried it through to a title in Cincinnati and then kept right on going at Flushing Meadows, where he was the runner-up to Dominic Thiem last year.

"I'm happy where I am, I'm happy with how things are, and I'm happy with how things were the last few months," the fourth-seeded German said.

"I'm in the quarter-finals now, and from here on, the matches will definitely not get easier."

It was another economical performance against 13th-seeded Sinner as Zverev broke serve once in each set while blasting 17 aces at Arthur Ashe Stadium.

Next Zverev will take on one of the tournament's many surprise packages in South African Lloyd Harris, who reached a first grand slam quarter-final with a 6-7 (6-8) 6-4 6-1 6-3 victory over 22nd-seeded Reilly Opelka.

Meanwhile, Italian sixth seed Matteo Berrettini overcame a second-set wobble to beat German qualifier Oscar Otte 6-4 3-6 6-3 6-2 and return to the last eight at Flushing Meadows for the second time in three years.

Berrettini was tested by Otte, whose surprise run came to a crashing end when he fell at 1-1 in the fourth set and injured his wrist.

with agencies

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